The present invention relates to a security strike plate that secures an entry door against being kicked in by virtue of strike plate failure during an attempted forcible entry.
Typical commercially available strike plates are attached to door jambs by wood screws, and have an opening through which the lock bolt of a keyed lockset or the dead bolt of a dead bolt installation passes into a receptacle carved out of the door jamb. When closed and locked, the outer vertical edge of the entry door rests against a door stop which can be a separate piece of wood attached to the door jamb, or the door stop and jamb milled from a single piece of wood. Typically the only thing securing the strike plate to the door jamb are two wood screws passing through openings in the strike plate located above and below the bolt receiving opening. Since the door stop is located on the exterior side of the door and strike plate, it provides no resistance to a door being forced inwardly from the outside. It is common for someone wishing to break into a dwelling through an entry door to merely kick the door until the screws securing the strike plate, or the door jamb to which the strike plate is attached, give way and the door is forced open.
The prior art has suggested a number of security means for preventing the wood screws of the strike plate from giving way during forced entry. Many employ additional wood screws which provide little added protection.
One device, described in U.S. Pat. No. 5,088,780, describes a security lock-keeper plate which can be used in conjunction with an existing strike plate or alone. A lower face plate forms the strike plate portion and an upper face plate, connected to the lower face plate by a center section adapted to seat against the edge of a door stop rail, rests against the outer face of the door stop. The upper face plate is attached to the wall studs by means of a large screw. However, the screw head can be dislodged from the upper face plate during forcible entry, and since the screw head is located on the outside of the door it can be accessed and removed by someone attempting a forced entry.
U.S. Pat. No. 4,809,400 describes a strike plate formed from a blank having a portion like conventional strike plates, and a tab extending from the conventional strike plate portion that can be folded to form a U-shaped member having aligned apertures for receiving a buck pin. The U-shaped member is inserted into a notch cut into the door stop. However, the head of the buck pin is on the outside of the door and can be accessed and removed by someone attempting a forced entry. In addition, to install this device the code required weatherstripping that fits into a slot at the juncture of the door stop and door jamb would have to be cut away to accommodate the device, thereby compromising the integrity of the weatherstripping.